Carbodiimides have proven useful in many applications, for example as hydrolysis inhibitors for ester-based thermoplastics, polyols, polyurethanes, etc.
It is preferable to use sterically hindered aromatic monocarbonyl diamides therefor. Especially 2,6-diisopropylphenylcarbodiimide is well known in this connection. However, these carbodiimides have the disadvantage of being volatile even at low temperatures. They are thermally unstable and can eliminate volatile substances (offgassing). Other carbodiimides, as described in EP 0 628 541 A1, are based on special raw materials which are costly to obtain. They also have high viscosities at room temperature which impedes handling of these carbodiimides. Furthermore, in certain PU, PET, PLA or lubricant applications, their reactivity and/or their stabilizing effect is insufficient at the concentrations used as standard. Polymeric carbodiimides based on inexpensive raw materials, such as those described in DP-2248751 and U.S. Pat. No. 2,941,983, are not sufficiently sterically hindered and do not show a good hydrolysis-inhibiting effect.